Storage tank



Aug. 31, 1965 R. w. BoDLEY 3,2()3,574`

sToRAGE TANK Filed Sept. 27, 1961 2 Sheets-Shee'l'. l

INVENTOR. ROBERT w. BODLE Y BY W jw, fiz'ww Y' W TTYS.

Aug- 31, 1965 R. w, BoDLEY 3,203,574

STORAGE TANK Filed Sept. 27. 1961 2 Sl'zeets-Sheei'I 2 INVENTOR. ROBERTW BODLEY t BY 76 7W W* W TTYS United States Patent O `3,'203,`574STGRAGE TANK Robert W. Bodley, Highland, Ind., assignor to Union Tank'Car lcompany, Chicago, Ill., a corporation of 'New Jersey Filed Sept.27, 1961, Ser. No. '141,110 14 Claims. (Cl. 220-245) The presentinvention relates to storage tanks of the fiXed and fioating roof typeand, more particularly, relates to a storage tank that is capable ofventing to the atmosphere vapors which have formed beneath the floatingroof.

Fixed roof or closed roof storage tanks embodiying floating roofs arewell known in the art. Although the floating roof rests or fioats uponthe stored liquid to prevent its volatilization, there are periodsduring normal operation of these tanks when it is impossible for thefioating roof to rest upon the liquid. Two such periods, for example,are when the tank is being filled for the first time (start-up) and whenit is being filled after having been cleaned. During these periods vaporformation cannot be avoided.

It has been the practice ia the past to vent vapors formed during theseperiods through the floating roof into the zone between the fixed roofand the floating roof. Though this etfectively removed the vapors frombeneath the fioating roof, it may create an explosive mixture of vaporand air in this zone which, if ignited, would cause complete destructionof the tank and loss of the-stored liquid. Thus this practice createdhazardous Operating conditions.

It is therefore an object of the instant invention to provide animproved storage tank embodying both a cone or fixed roof and a floatingroof.

It is another object of the instant invention to provide I storage tankscontaining floating roofs wherein vapors formed beneath the floatingroof are vented directly to the atmosphere, thereby precluding hazardousOperating conditions.

It is a further object in accordance with the previous object to ventthe vapors to the atmosphere without the vapors entering the zonebetween the fioating and fixed roofs of the tank.

It is a further object of the instant invention to provide in a storagetank a ventilating arrangement that is integrated with the structureordinarily required in storage tank constructions whereby theventilating feature is provided at relatively small additional eXpense.

It is a further object of the instant invention to provide in a storagetank a venting arrangement associated with a ladder or a support columnfor the fixed roof to exhaust to the atmosphere vapors formed beneathits fioating roof, the fluid and vapors being prevented from passinginto the zone of the tank above the fioating roof by the gas-tightrelationship existing between the fioating roof and the ladder orsupport column arrangement.

The above and other objects are realized in accordance with the presentinvention by providing a new and improved storage tank of the typeembodying both a fixed cone roof and a floating roof. The storage tankincludes a ventilating arrangement that vents vapors formed beneath thefloating roof directly to the atmosphere without passing through thezone between the floating and fiXed roofs. grated with structureconventionally embodied in storage tanks, for example, the access ladderor the support column for the fixed roof. Specifically, the ladder orsupport column between the exterior of the tank and the interior of thetank provides communication below the floating roof when it is in itsstart-up and Cleaning posi- The ventilating arrangement preferably isinte- ICC tions. The oating roof and ladder or support column are ingas-tight relation.

The invention, both as to its organization and method of operation,taken with further objects and advantages thereof, will best beunderstood by reference to the following description taken inconjunction with the accompanying drawings, in which:

FIG. 1 is a cross-sectional view of a storage tank embodying thefeatures of the present invention, illustrating the floating roof in itsCleaning position;

FIG. 2 is a fragmentary top plan view of the storage tank of FIG. 1taken along lines 2-2;

FIG. 3 is a fragmentary cross-sectional view taken along lines 3-3 ofFIG. 1;

FIG. 4 is a fragmentary cross-sectional view of the storage tank of FIG.1, illustrating the floating roof in its start-up position;

FIG. 5 is an enlarged fragmentary cross-sectional view of an embodimentof the storage tank of FIG. 1, illustrating the floating roof andassociated ladder construction; and

FIG. 6 is an enlarged perspective view of the sealing means shown inFIG. 5.

Referring now to the drawings, and more particularly to FIGS. 1-4, thereis illustrated a closed storage tank of the fioating-roof typeidentified generally by reference numeral 10. The storage tank 10 servesto store liquid, for example, petroleum products, which is fed to andwithdrawn from the tank 10 through suitable conduits and valvingarrangements (not shown) which communicate with the lower portion of thetank 10.

The tank 10 includes a circular floor 12 which is located on the groundand a generally cylindrical Shell 16 extending upwardly from theperiphery of the fioor 12-. The shell 16 supports the edge of a fiXedroof 18 that has an upwardly extending conical shape. In addition to theshell 16, Vertical columns (not shown) extending upwardly from the floor12 may be employed to internally support the fixed roof 18.

To provide access to the interior of the tank 10 a ladder, identifiedgenerally by reference numeral 22, is secured to the floor 12 andextends upwardly therefrom through the fixed roof 18 so that its upperend is adjacent to a conventional manway 24 (see FIG. 2).

To prevent volatilization of the liquid stored in tank 10, a fioatingroof, identified generally by reference numeral 28, floats on 'andextends over substantially the entire surface of the liquid. As is knownto those skilled in the art, the iloating roof 28 moves verticallywithin the storage tank 10 .as the level of the liquid within the tank10 changes. To prevent vapor loss, a suitable sealing arrangement 11 ofthe type disclosed and claimed in an application Serial No. 821,247,filed by Reign C. Ulm, on June 18, 1959, which issued as United StatesPatent No. 3,154,213 on October 27, 1964, and assigned to the sameassignee as the present invention, is supported by the fioating roof 28so as to frictionally engage the shell 16, irrespective of the positionof the floating roof 28 within the tank 10. The floating roof 28 issuitably apertured at 30 and 13 to accommodate the ladder 22 and theadjustable support members 41, respectively.

The construction of the floating roof 28 in general is immaterial to theinstant invention and the illustrated construction is merely exemplary.The fioating roof 28 in FIG. 1 is of the type disclosed and claimed inan application Serial No. 122,497, filed by Robert W. Bodley, on July 7,1961, which issued as United States Patent No. 3,134,501 on May 26,1964, and assigned to the same assignee as the present invention. It maycomprise a plurality of flanged Sections which have been securedtogether at joints, indicated generally by reference numeral 39, to forma substantially continuous bottom surface 38 which rests upon the liquidstored in the tank. An upwardly extending L-shaped flange 40 ispositioned around the periphery of the floating roof 28. The Sealingarrangement 11 is secured to the vertically disposed leg of the L-shapedflange 40. The horizontally disposed leg of L-shaped flange 40 hasopenings therein adapted to engage the adjustable support means 41, aplurality of which are disposed around the periphery of the floatingroof.

Supporting the floating roof 28 above floor 12 during the start-up andCleaning Operations, which Will be dis- Cussed in more detailhereinafter, are adjustable support means 41, which comprise a sleevemember 42 which extends through the fiange 40 and the hole 13 in roofbottom 38. Sleeve member 42 is secured to the floating roof by weldingor the like and is adapted to slidably receive a pipe-like supportingleg 43, which has transverse holes 48 (see FIG. 4) and 48a therein atdifferent levels for reasons apparent hereinafter. Sleeve 42 has a pairof aligned transverse holes. Thus when hole 48 in supporting leg 43 isaligned with the holes in sleeve 42, a large pin 44 may be insertedthrough the aligned holes to rgidly position the supporting leg 43 asshown in FIG- URE 1. Support legs 43 of adjustable support means 41 restupon pads 49 when they support the floating roof.

Extending upwardly from the floating roof around the periphery of theopening 30, through which ladder 22 extends, is an inverted L-shapedfiange 45. A Sealing means 46, which prevents vapor and fluid fromentering the zone within the tank above the floating roof, is secured bysuitable means, such as nuts and bolts or screws, to the annular,horizontally disposed leg of flange 45. As shown in FIG. 3 Sealing means46 contains an opening or slot which Conforms to the horizontalcross-sectional Configuration of ladder 22, i.e., two CirCular-shapedopenings connected by a long reCtangular-shaped slot. The opening isslightly, proportionally smaller than the crosssectional dimensions ofthe ladder 22 so that a tight seal is eifected between the seal andladder. Sealing means 46 prevents vapor and fluid from flowing throughpassageway 30 to the other side of floating roof 28. Sealing means 46 ismade of rubber, plastic, fabric or other suitable fiexible, gasimpervious material.

Considering now in more detail the venting arrangement of the instantnvention wherein vapors beneath the roof are exhausted directly to theatmosphere, the ladder 22 Comprises a pair of spaced, upright, hollowside rails 31 and 32 interconnected by a plurality of rungs 33. Theladder 22 extends through the floating roof 28 and is secured to thefloor 12 of the tank 10. The rails 31 and 32 are hollow and form theventing passageways which communicate with the interior of the tankthrough openings 34 and 35, respectively, in the rails. The ventingpassageways in rails 31 and 32 communicate with the outside of the tankthrough openings 26 and 27, respectively, at the uppermost ends of therails. Vent caps 37 are securely positioned above these openings toprevent foreign matter from entering the storage tank 10.

Having described the apparatus, its operation will be understood fromthe following discussion. FIG. 4 illustrates the floating roof as itappears during the start-up operation; that is, When it is being filledfor the first time. During start-up the floating roof must be supportedabove the floor, since the liquid to be stored must have room to enterthe storage tank beneath the floating roof. In the instant illustratedapparatus, the floating roof is supported about 3 feet above floor 12 bysupport legs 43 which are secured to sleeve 42 by means of pin 44extending through the holes in sleeve 42 and hole 48a in support leg 43.Liquid to be stored in the storage tank is fed by suitable means (notshown) into the tank below the floating roof. During this start-upoperation there will obviously be a period of time in which the floatingroof will not rest upon the liquid in the storage tank. As a result,vapors will form between the liquid and floating roof. If this vapor isnot removed the floating roof will rise on the vapor, rather than on theliquid as desired.

As explained hereinbefore, in prior art floating roof constructionsthere were provided means for venting this vapor from below the floatingroof to the zone between the floating roof and the fixed roof of thestorage tank. This was undesirable as it created a combustible mixtureof vapor and air in this zone.

In the instant invention, however, this problem during start-up isavoided by means of the venting passageway and opening 35 in the rail 32of ladder 22. While the liquid is being passed into the storage tankbelow the floating roof 28, any vapor which is formed is vented throughopening 35 and the venting passageway in rail 32 to the atmosphere. Thusby the time the entering liquid has reached the level of the floatingroof shown in FIG. 4, all the vapor has been expelled from beneath thefloating roof through the venting passageway to the atmosphere and theroof will rise on the level of the liquid, rather than on vapor abovethe liquid. Once the floating roof begins to rise it may, of course,ascend substantially to the top of storage tank 10 depending on thelevel of the liquid stored.

In the instant embodiment, opening 35 is positioned such that when thefloating roof is in its start-up position it is between the Sealingmeans 46 and the level of the floor bottom 38 of roof 28. It will beunderstood, however, that thongh this is the preferred position of thisopening, it will suffice if any portion of the opening 35 is above thebottom level 38 of roof 28. In this manner all of the vapor formed belowthe floating roof may be expelled to the atmosphere while simultaneouslysealing otf the zones below and above the floating roof.

Periodically the tank must be cleaned. This may be occasioned by the useof the tank to store 'a different liquid or merely to remove sediment orthe like formed during continued storage of similar materials. Toprepare the tank for Cleaning, a workman, prior to removing the liquidfrom the tank, will adjust support members 41 to their Cleaningposition. This requires the workman to enter the tank via manway 24 andladder 22 and get on the top of floating roof 28. There he adjusts eachsupport means 41 (which are in the start-up position) by removing pin 44and lowering pipe 43 in sleeve 42 such that hole 48 is in line with theholes in sleeve 42. The pin 44 is then inserted through the alignedholes and the support means is in the Cleaning position. Thus as theliquid is drained from the storage tank 10 the adjustable support legs43 will Come to rest upon pads 49 and support the floating roof aboutsix feet from the floor 12 of the tank as shown in FIG. 1. After all theliquid has been removed from the storage tank 10 a man or men may entertank 10 via manholes (not shown) located below the floating roof andClean the floor and the walls of the tank.

When the tank is being filled after a Cleaning operation there will be`a period of time in which vapor may form between the liquid and thefloating roof. However, the opening 34 in rail 31 permits the vapor topass via the venting passageway to the atmosphere. As illustrated,opening 34 is |positioned such that When the floating roof is in itsCleaning position it is between the Sealing means 46 and the level ofthe floor bottom 38 of roof 28. It will be understood, however, thatthough this is the preferred position of this opening, it suflices ifany portion of opening 34 is above the bottom level 38 of roof 28. Inthis manner all of the vapor formed below the floating roof may beexpelled while simultaneously Sealing off the zones below and above thefloating roof. Opening 34 and the venting passageways in rail 31therefore operate in the same manner after Cleaning as opening 35 andthe venting passageway in rail 32 operate during start-up.

Once the floating roof begins to rise on the liquid, generally a workmanwill enter the storage tank and place the supporting legs in theirstart-up position. The tank is then ready for normal operation. That isthe liquid level may fiuctuate between substantially the height of thestorage tank to about three feet above the fioor of the tank and thefloating roof will at all times during such fluctuations rest upon theliquid.

Referring now to FIGS. 5 and 6 there is shown a modified sealing meansto prevent vapor or liquid from flowing through an opening 6G infloating roof 28 through which the venting ladder 22 extends. Thesealing means, indicated generally by reference numeral 7d, comprisestwo mating members 71 and 72 which have Vertical members 75 havingsurfaces which conforrn generally to the contour of the side of theladder 22. Each Vertical member 75 is connected to a horizontallydisposed lip 77 which has a pair of Vertical, laterally extendingflangcs 74. Each Vertical member 75 has a pair of longitudinal,vertically disposed flanges 76. The two matng members 71 and 72 areplaced around ladder 22 above the floating roof 28 and secured togetherby means of nuts and bolts or the like (not shown) which extend throughsuitable holes in anges 76 and 74. Suitable rubber or plastic gaskets 78are placed between the fianges 76 and 74 prior to securing the matingmembers 71 and 72 together.

The floating roof 28 has an L-shaped flange 61 which extends upwardlyaround the periphery of the opening 6G. Its horizontally disposed,annular surface 62 will seat the sealing means 79 which is slidablymounted around ladder 22. A suitable rubber or plastic gasket 63 issecured to the upper surface of leg 52 to insure a good Seal betweensealing means 70 and the annular surface 62.

Referring now specifically to FIG. 5 the floating roof and sealing meansare shown as they would appear when the floating roof is in its clean-upposition, i.e., in the same position shown in PIG. l. The dotted linesin FIG. 5 indicate the position of the floating roof and sealing meanswhen the floating roof is in its start-up position, i.e., the sameposition shown in FIG. 4. Basically the operation of the venting systemand floating roof dis-' cussed hereinbefore is applicable to the instantembodiment, the only distinction being that sealing means 70 rides uponsurface 62 of flange 61 and is maintained in that position merely by itsown weight without the necessity for any physical attachment between thesealing means and this fiange. In addition it will be noted thatopenings S0 and 90 in the rails are positioned to communicate with thetank below the floating roof 28 when it is in its cleaning and start-upposition, respectively, and extend upwardly slightly above the bottomlevel of the floating roof 28 when it is in these positions tocompensate for liquid displacement caused by the weight of the roof 28.In this manner, all the vapor formed below the floating roof may beexpelled prior to the roof 28 beginning to float.

Though the instant venting arrangement has been illustrated anddescribed in conjunction with a ladder in the storage tank, it will beunderstood that it may also be effected through the Vertical, hollowsupporting columns employed to give additional support to the fixed roofof the storage tank. In that instance the Vertical support column wouldextend through the fiXed roof and open to the atmosphere as do the railsof the ladder discussed hereinbefore. One column may effect venting inboth the situations discussed hereinbefore by having two appropriatelypositioned openings therein. In the alternative, venting may be eifectedby two supporting columns, one column eifecting venting during start-upand the other effecting venting as the tank is being filled aftercleaning. In all other respects the sealing means, vent caps and thelike would be similar with the exception that they would be adapted toreceive and cooperate with the venting support columns rather than theladder.

Furthermore, it will be understood that the Various venting arrangementsdescribed herein also will allow air from outside the tank to enterbetween the floating roof and the liquid while the tank is being emptiedvafter the floating roof is resting in its cleaning or start-upposition. In this manner, a partial vacuum beneath the floating roof 28may not be formed.

While several embodiments described herein are at present considered tobe preferred, it is understood that various modific-ations andimprovements may be made therein, and it iS intended to cover in theappended claims all such modifiactions and improvements as fall withinthe true spirit and scope of the invention.

What is desired to be claimed and secured by Letters Patent of theUnited States is:

1. A closed storage tank containing a floating roof therein and meansfor venting to the atmosphere vapors formed beneath said floating roof,'said means comprisng a substantially vert'ical member positioned withinsaid tank and extending to the bottom of said tank, said Vertical memberextending through an opening in said floating roof, said Vertical memberhaving a venting passageway therein which communicates with theatmosphere and with said tank below said floating roof, and sealingmeans cooperating. with said floating roof and said Vertical member toprevent the flow of vapors from beneath said floating roof to the top ofsaid floating roof, said sea'ilng means comprising an elongate Verticalsealing member having an opening therein which is adapted to slidablyreceive said Vertical member, said sealing member being adapted to benon-attachably seated upon said floating roof around the periphery ofsaid opening in said floating .roof through which said Vertical memberextends, said sealing member comprising two mating members which areconnected laround said Vertical members and adapted to slide verticallyupon said Vertical member with the movement of said floating roof.

2. A closed storage tank containing a floating roof therein having astart-up position and a higher cleaning position and means for ventingto the atmosphere vapors formed beneath the floating roof as saidstorage tank is being filled during start-up and after cleaning, saidmeans comprising a ladder vertically positioned within said tank, sa'idladder having a first and second rail each having a venting passagewaytherein, said venting passa ge' ways communicating with the exterior ofsaid tank, one of said passageways communicating with the interior ofsaid tank through an opening `in said first rail located below thefloating roof when said floating roof is in the start-up position andsaid other venting passageway communicating with the interior of thetank through an opening in said second rail located above the opening insaid first rail and below the level of said floating roof when saidfloating roof is in the cleaning position.

3. The storage tank of claim 2 wherein at least a portion of saidopening in said first rail is located above the bottom of said floatingroof when said floating roof is in the start-up position.

4. The storage tank oficlaim 2 wherein at least a portion of saidopening in said second rail is located above the bottom of said floatingroof when said floating roof is in the cleaning position.

5. A closed storage tank containing a floating roof therein and meansfor venting to the atmosphere vapors formed beneath said floating roof,said means comprising a ladder vertically positioned within said tankand eX- tending to the bottom of said tank, said ladder extendingthrough an opening in said floating roof, said ladder having a ventingpassageway therein which communicates with the atmosphere and with saidtank below said floating roof, and sealing means cooperating with saidfloating roof and said ladder to prevent the flow of vapor from beneathsaid floating roof to .the top of said floating roof.

6. A closed storage tank oontaining a floating roof therein and meansfor venting to the atmosphere vapors formed beneath said floating roof,said means comprising a ladder vertically positioned within said tankand extending to the bottom of said tank, said ladder extending throughan opening in said floating roof, said ladder having a ventingpassageway therein which communicates with the atmosphere and with saidtank below said fioating roof, and sealing means cooperating with saidfloating roof and said ladder to prevent the fiow of vapor from beneathsaid fioating roof to the top of said floating roof, said sealing meanscomprising a flexible member secured to said fioating roof, and havingan opening therein which conforms substantially to the cross-sectionalconfiguration of the ladder, said ladder extending through said openingin said flexible member.

7. A closed storage tank containing a fioating roof therein and meansfor venting to the atmosphere vapors formed beneath said fioating roof,said means comprising a ladder vertically positioned within said tankand extending to the bottom of said tank, said ladder extending throughan opening in said floating roof, said ladder having a ventingpassageway therein which communicates with the atmosphere and with saidtank below said fioating roof, and sealing means cooperating with saidfloating roof and said ladder to prevent the flow of vapor from beneathsaid floating roof to the top of said fioating roof, said sealing meanscomprising an elongate member having an opening therein which is adaptedto slidably receive said ladder, said seal'ing means being a-dapted tobe seated upon said fioating roof around the periphery of said openingin said fioating roof through which said ladder extends.

8. The storage tank of claim 7 wherein said sealing member comprises twomating members which are connected around said ladder and adapted toslide vertically upon said ladder with the movement of said floatingroof.

9. A closed storage tank containing a floatng roof therein and means forventing to the atmosphere vapors formed beneath said floating roof, saidmeans comprising a ladder vertically positioned within said tank andextending to the bottom of said tank, said ladder extending through anopening in said floating roof, said ladder having a venting passagewaytherein which communicates with the atmosphere and with said tank belowsaid fioating roof, and sealing means cooperating with said floatingroof and said ladder to prevent the flow of vapor from heneath saidfloating roof to the top of said floating roof, said sealing meanscomprising two elongate members having Vertical surfaces which conformto the side configuration of said ladder, said elongate members beingconnected together around said ladder with said Vertical surfaces inslidable contact with said ladder, said elongate members having fiangesadapted to rest upon said fioating roof around the periphery of theopening in said floating roof through which the ladder extends.

10. The storage tank of olaim 9 wherein said floating roof has a flangeextending upwardly around the periphery of the opening in said fioatingroof for said ladder, said flange containing a horizontally disposedleg, said sealing means bei-ng seated upon said horizon- .tally disposedleg of said flange, and a gasket :means between said horizontallydisp'osed flange and said sealing means.

11. A closed storage tank containing a floating roof therein having astart-.up .position and a higher oleaning .position and means forventing to the atmosphere vafpors forrned beneath the fioating roof assaid storage tank is being `filled during start-up and after cleaning,said means comprising a ladder vertically positioned within said tank,said ladder having a first vand second rail each having a ventingpassageway therein, said venting .passageways communicating with theexterior of said tank, one of said passageways communicating with theinterior of said tank through an opening in said first rail locatedhelow the .floating roof when said floating roof lis in the start-upposition and said other passageway communicating with the interior ofthe tank through an opening in said second rail located above theopening in said first rail and below the level of said floating roofwhen said fioating roof is in the Cleaning position, and sealing meanscooperating with said ladder and said floating roof to prevent vaporfrom flowing between said ladder and said fioating roof to the top ofsaid floating roof.

12. The storage tank of olaim .11 wherein said tloating roof has anopening therein through which said ladder extends, said roof having anupwardly extending flange around the .periphery of said opening, `saidsealing means `being secured .to said flange, at least a portion of saidopening in said first rail fbeing located above the bottom of saidfloating roof when said floating roof is in the start-up position and atleast a portion of said opening in said 'second rail being located abovethe bottom of said fioating roof when said floating roo-f is in thecleanin g ip osition.

13. The storage tank Vof claim 12 wherein said sealing means cornprisesa flexib'le member having an opening therein which conforms to thecross-'sectional configuration of said ladder, said ladder extendingthrough said opening in said fiexible member.

14. The storage tank of claim 13 wherein said opening in said first railis between the level of the bottom of said floating roof and saidsealing means when said floating roof is in the start-up position andsaid opening in said second rail is between the level of the bottom ofsaid floating roof and said sealing means when said float- `ing roof isin the cleaning position.

References Cited by the Examiner UNITED STATES PATENTS 1,529,767 3/25Briers et al. 220-26 1,580,194 4/26 Glass 220-26 1,592,524 7/26 Holt220-26 '1,754,597 4/30 Bohnhardt 220-26 `1,816,l24 7/31 Patterson 220-262,461,537 3/49 Feild 220-26 X 2,6253114 1/53 Moyer 220-26 X THERON E.CONDON, Primary Examiner.

1. A CLOSED STORAGE TANK CONTAINING A FLOATING ROOF THEREIN AND MEANSFOR VENTING TO THE ATMOSPHERE VAPORS FORMED BENEATH SAID FLOATING ROOF,SAID MEANS COMPRISING A SUBSTANTIALLY VERTICAL MEMBER POSITIONED WITHINSAID TANK EXTENDING TO THE BOTTOM OF SAID TANK, SAID VERTICAL MEMBEREXTENDING THROUGH AN OPENING IN SAID FLOATING ROOF, SAID VERTICAL MEMBERHAVING A VENTING PASSAGEWAY THEREIN WHICH COMMUNICATES WITH THEATMOSPHERE AND WITH SAID TANK BELOW SAID FLOATING ROOF, AND SEALINGMEANS COOPERATING WITH SAID FLOATING ROOF AND SAID VERTICAL MEMBER TOPREVENT THE FLOW OF VAPORS FROM BENEATH SAID FLOATING ROOF TO THE TOP OFSAID FLOATING ROOF, SAID SEALING MEANS COMPRISING AN ELONGATE VERTICALSEALING MEMBER HAVING AN OPENING THEREIN WHICH IS ADAPTED TO SLIDABLYRECEIVED SAID VERTICAL MEMBER, SAID SEALING MEMBER BEING ADAPTED TO BENON-ATTACHABLY SEATED UPON SAID FLOATING ROOF AROUND THE PERIPHERY OFSAID OPENING IN SAID FLOATING ROOF THROUGH WHICH SAID VERTICAL MEMBEREXTENDS, SAID SEALING MEMBER COMPRISING TWO MATING MEMBERS WHICH ARECONNECTED AROUND SAID VERTICAL MEMBERS AND ADAPTED TO SLIDE VERTICALLYUPON SAID VERTICAL MEMBER WITH THE MOVEMENT OF SAID FLOATING ROOF.